Category — ADHD: Genetics

Obviously, being pregnant can be stressful in itself, but current research shows that stress can affect fetal development which may lead to long-term problems including ADHD.

Dr. Vivette Glover of Imperial College London, surveyed pregnant women at her hospital. Of these, nearly one quarter felt anxious and depressed due to stressors including work, money, arguing with spouse, and moving to accommodate a larger family. When compared to their non-stressed counterparts in this research, the babies of the stressed mother had lower birth weight, lower IQ, slower cognitive development, and more anxiety. Lower birth weight has been an indicator for coronary heart disease in later life.

In 2007, research in the Journal of the American Academy of Child and Adolescent Psychiatry indicated that being stressed during pregnancy is as detrimental for the baby’s development as smoking or being obese. Glover’s research reveals why and how this happens: stress produces the hormone cortisol. An abundance of stress can actually diminish the barrier enzyme that inhibits cortisol from reaching the fetus. Costisol impacts fetal brain development.

According to Glover, “People used to think that if something was congenital, apparent at birth, it had to be genetic. In fact it can be an in-vitro reaction of genes and environment.”

Glover also contends that her research shows stress greatly increases the likelihood of a child having ADHD (attention-deficit hyperactivity disorder), cognitive delay, autism , anxiety and depression. 

Glover’s research reinforces previous data from the UK where stress was shown to increase the risk for development of ADHD. In that research, the women who experienced the most stress doubled the chances of developing ADHD.

“The organs are forming during the first trimester of pregnancy, but the brain is developing all the way through,” Glover explains. “The organs are sensitive while they are forming and, once formed, they are harder to change.”

“In evolutionary terms, stress perhaps prepares the child for survival in a stressful environment. If a child is anxious and has attention deficiency, it will be very alert to danger. This may once have been adaptive, beneficial for the child, but it isn’t any more,” Glover says.

Significantly, Glover’s research implies that the changes may be on a genetic level so that it may be passed on generation to generation.

Therefore, it’s important to realize that taking care of ourselves during pregnancy is more important now than ever. Small efforts like seeking health services early, meditating, eating a balanced diet, taking pre-natal vitamins, and laughing are good practices.

Minimizing stress by maintaining a consistent schedule both at work and at home is a good idea.

Research over the past decade has been relatively inconclusive regarding the etiology of ADHD and its genetic links. The January 07, 2009 special issue of American Journal of Medical Genetics (AJMG): Part B: Neuropsychiatric Genetics presents a comprehensive overview of the latest genetic research of ADHD. In search of the ADHD holy grail, researchers have attempted to identify specific genes that underlie the disorder in the hopes that gene discovery will lead to better treatments for the disorder.

The studies cited in the AJMG indicate that one genetic marker may be associated with ADHD symptoms with the possibility that many genes are involved in ADHD. Each of these genes may play small roles in their overall presentation of ADHD symptoms. The currents studies then are inconclusive and suggest the need for larger studies a) to determine if there are genetic mechanisms underlying ADHD, b) to determine what these mechanisms do if they exist, and c) to determine whether these initial findings can be confirmed.

An important issue needs to be raised here: If one can find a genetic marker and the various genes involved in ADHD, is it therefore a disease like diabetes, cancer, or atherosclerosis? Or is it a genetic trait like red hair, crooked teeth, or freckles? Personally, it seems to me to be more of a trait than anything else. Even the noted ADHD expert, Dr. Ed Hallowell and his colleague, Dr. Peter Jensen, have indicated they perceive ADHD as a trait.

The second issue that needs to be raised here is: What is it that the researchers can do with the genetic information they are seeking? The answer to this question is medication. Most of the genetic studies have leaned toward a genomic search for genes that may someday be used to predict which children respond most favorably to the stimulant medications. The current studies indicate that, although there are likely to be genetic factors that are associated with stimulant efficacy in children with ADHD, there are no single genes with a very large impact on treatment response. This may be because ADHD is a conflation of diffused attention, poor organization, hyperactivity, etc. Are there genetic markers for each of these individual characteristics?

This presents us with the problem of antecedence (chicken or the egg). It appears that ADHD is a conflation of a variety of characteristics. This is precisely how it is diagnosed. These characteristics could be acquired in one of two methods: They could be genetic (heritable) or they could be learned. One can learn to be disorganized, hyperactive, or even have diffused attention. Most of us experience this now in our busy, noisy existence on this planet. Does this change our genetic makeup?

We know that when we learn something, certain genes are switched on which activate messenger RNA to build neural networks supporting long-term memory. Therefore, we are substantially changing our genetic makeup. The brain is incredibly malleable or labile. This is both significant and promising. We can and do shape it through our various daily activities. It would hold then, that we can change our diffused attention into focused attention, our disorganization into organization, and our hyperactivity into calm behavior. However, if we obdurately argue that ADHD is a disorder or disability, then hope for this change is diminished if not extinguished. Now is the time to realize that there is hope for persons with attention challenges; change is quite possible and achievable. Genetic research points us in this direction. It’s past time to follow

Research shows a gene link to ADHD

The head of child psychiatry at the Royal Children’s Hospital (University of Melbourne, Australia), Professor Alasdair Vance, thinks that children with ADHD have impaired brain function most likely linked to a genetic condition occurring during pregnancy.

Dr. Vance believes he has conclusive evidence that key areas of the brain do not develop as quickly in children with ADHD. These areas, he posits, are linked to a child’s understanding of time and space as well as the ability to use working memory.

“So their ability to read other people’s body language, to pick up on the nuances of what their peer group are up to, would clearly be affected by the sort of developmental delays in brain development that we’ve identified,” he said.

“The most exciting part of this research is the opportunity to understand in detail the brain dysfunction in this group of children so we can better understand how, by changing the child’s environment, facilitated by medication treatments, we can maximize their learning.”

Vance used fMRI on an unmedicated group of boys aged eight to 12 who were diagnosed with ADHD. The fMRI enabled Vance to examine their brains while performing mental tasks. This data was compared to a group of healthy children. Vance said the data demonstrated that ADHD was not just a behavioral issue.

“If it was, one would expect the child’s brain would be functioning normally and that at some level they are making choices to behave in this way. This suggests they are actually activating their brain differently when they are doing the same task as a healthy kid.”

In an interview with the Brisbane Times, Vance, “…believes the research strongly suggests ADHD is a genetic condition occurring most probably during the second trimester of a woman’s pregnancy, but which can be modified through medication and by adapting the child’s environment.”

“I’m not saying that because you have such brain changes the only treatment is medication. Environmental cueing can help those compensatory brain networks to develop.”

“Helping teachers and parents understand how to more frequently cue a child with ADHD through such means as positive reinforcement when the child exhibits desired behavior and through emotional connections that reward the child for better attitudes, are just some of the ways in which the condition can be helped, Professor Vance says.”

“The number and quality of empathic, confiding, nurturing, flexible and adaptive human relationships can build resilience, build compensation or, if absent, make ADHD symptoms worse,” he said.

Vance’s results are preliminary. Furthermore, one cannot forget that ADHD is diagnosed from subjective analysis; it is one of the few diagnoses that can be made over the telephone since it involves acknowledging a series of characteristics or behaviors performed over time. So, we have a problem of antecedence; Vance examined boys that were subjectively diagnosed with ADHD to compare them with boys that were not diagnosed. Does the subjective diagnosis present a problem in this research? I would think so. Could it also be possible that the brain changes in the fMRI could occur as a result of conditioning, environmental toxins, etc? Possibly. Is it equally possible that Vance’s data only accounts for one possible cause out of many? Likely. That’s why I would contend the results are preliminary. We’ll see if the future proves me wrong on this one.

On a positive note Vance does seem to understand neuroplasticity. He does see value in behavioral shaping, compensatory training, etc. While his research is NOT the Holy Grail of ADHD, there is light at the end of the tunnel if we are forging ahead in our understanding of neuroplasticity from research like this.

Clearly, there is no current research (2005) that has determined that ADHD is genetic either partially or entirely. While empirical data suggest that a genetic link exists, research is still sparse as scientists primarily focus on childhood onset of the disorder with little research on adult AD/HD.

Andrea Chronis of the University of Maryland  has focused on AD/HD mothers and their performance as parents. In her study of 70 families with elementary-school-age children she found that:

• Mothers of ADHD children are 24 times as likely as the average woman to have it
• Fathers of ADHD children are 5 times higher than average to have it
• The mothers often weren’t very involved with their children
• The mothers had few skills to cope with their children
• The mothers didn’t give praise or show affection regularly
• Discipline was inconsistent
• Most of their children also had ADHD

While Chronis’ research does not prove a genetic link, it offers strong support for the theory. And while poor parenting may exacerbate ADHD symptoms, it does not cause ADHD. Thus, the aforementioned poor parenting skills would likely contribute to worsening their childrens’ symptoms. This would lead one to think that parenting skills/counseling should be a primary consideration for families with ADHD.